TNFalpha- and Fas-induced apoptosis in the liver in experimental animals in closely associated with liver in disease in patients. We have developed a model systems to study apoptosis in primary cultures of hepatocytes. We wish to assess the role of NFkappaB in the apoptotic pathways induced by TNFalpha and Fas. The underlying hypothesis is that NF-kappaB is anti-apoptotic via the induction of genes that affect DISC (Death-Inducing Signaling Complex) formation, the mitochondrial permeability transition (MPT), and caspase activation. This proposal wishes to examine the following specific aims: 1. To assess the effect of NF-kappaB on the apoptotic signaling pathways mediated by TNFalpha and Fas. 2. To determine which genes are induced by NFkappaB in response to TNFalpha and Fas in cultured hepatocytes. 3. To demonstrated a protective role for NO and iNOS in TNFalpha- and Fas-mediated apoptosis in hepatocytes. 4. To test the requirement of GD3 in TNFalpha- and Fas-mediated apoptosis in hepatocytes. It is the balance between these anti-apoptotic and apoptotic signals that determines the fate of the hepatocyte in this pathophysiological process.